1. Field of the Invention
The present invention relates to protective covers for valves and manholes, and more specifically to a method and apparatus for securing valves and manholes by means of a locking cover.
2. Description of Prior Art
The general principles of locking doors, hatches, and vaults are widely known. Many designs use the principle of locking rods or bolts being moved radially into or out of a locking position by some rotating, lever, or gear drive mechanism. Some designs include the use of a keyed cylinder, combination lock, or timer mechanism, or a combination of all in order to secure the locking rods or bolts into position. The application of such devices has extended to safe doors, bank vault doors, ship hatches, aircraft hatches, and the like.
Yet one application in which there has been a need for decades for a practical, reliable method and apparatus for securing access has been that of valve covers, manhole covers, and cover plates for boxes, pits, and vaults. Wherever valves exist that can be manually turned and that can be accessed by persons who have no valid reason to turn them, or vaults containing sensitive equipment, there is a need for a locking valve cover. Wherever access to conduits such as sewer or storm drain pipes, underground communications lines, electric junctions, natural gas main controls, or the like is available through manholes, valves, above or below-ground buildings or vaults, a locking cover can provide necessary security.
By way of example, community water main valves are frequently buried underground, with access provided to them by a shroud that extends from the underground conduit to the surface. The opening of the shroud is covered by a small, usually round, cast iron cover that can be removed by a prying tool, or even by a person's fingers. Access points to these valves are frequently found in public places, such as on streets or sidewalks. Electrical and telephone cables are frequently located in underground pipes or conduits, with access provided by manhole. The manhole access is usually secured by a cast iron cover. Storm drains and sewer systems are similarly accessed.
There have been some previous lockable manhole covers devised. However, until the development of the present invention, no relatively inexpensive, weatherproof, convenient, reliable, and easy to assemble device that would provide security for the widespread, already-installed underground conduit systems, as well as future systems, has existed.